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A nanodevice that exploits quantum physics could act as an engine that is driven not by thermal energy, but by the act of making measurements.

In quantum mechanics, the act of measuring a system alters its state. A team led by Alexia Auffèves at the French National Center for Scientific Research in Grenoble proposes a quantum engine, in which the amount of energy produced is extracted by quantum fluctuations induced by measurements of the system. The engine produces photons that propagate in a circuit, and can be used later on for quantum computations. The faster the measurements are repeated, the more efficiently the engine runs.

The authors have simulated their quantum engine and say it could be demonstrated on existing lab equipment.

Tomato plants have a novel defence against caterpillars that eat them: they make their tissue so unappealing that caterpillars opt instead for cannibalism.

John Orrock and his colleagues at the University of Wisconsin–Madison, sprayed tomatoes (Solanum lycopersicum) with differing concentrations of methyl jasmonate, which is known to induce plant defences. Beet armyworm (Spodoptera exigua) caterpillars on plants where defences were strongly induced started to eat each other sooner and were about twice as likely to consume each other as those on control plants, over the course of the experiment.

The team found that plants with switched-on defences produced tissue of lower quality, and their would-be predators tried to supplement this non-nutritious food by feasting on others of their kind.

Astronomers have discovered complex organic molecules in a cloud of gas and dust that is on its way to becoming an infant star. It is the youngest protostar yet found to contain such compounds.

A team led by Chin-Fei Lee of the Academia Sinica Institute of Astronomy and Astrophysics in Taipei targeted an object called Herbig–Haro 212, which lies 400 parsecs (1,300 light years) away, in the constellation Orion. The embryonic star at its centre is only about 40,000 years old. Using the ALMA telescope in Chile, the scientists detected complex organic molecules, including methanol, above and below the protostellar disk.

The discovery suggests that such materials, which are building blocks of life, are available very early in the evolution of solar systems.

But benefits for formal maths learning quickly wear off, a large study in India finds.

Preschool maths games can boost children’s mathematical intuition, according to a large-scale classroom study in India.

Moira Dillon at New York University in New York City and her colleagues studied the effects of cognitive games on 1,540 children, most aged between 4 and 6, at more than 200 preschools in Delhi. Over the course of four months, some children played maths games, such as comparing numerical quantities and finding geometric shapes. Others played games to exercise their social skills, and others played no games.

Those that played maths games scored better in overall mathematical aptitude tests than those that played social games or no games. In particular, maths games enhanced non-symbolic, intuitive skills — such as the ability to approximate quantities — for up to 15 months, the length of the study period. Maths-trained preschoolers also showed short-term gains in symbolic mathematics, including knowledge of numerals and shape names, but these benefits disappeared during the first year of primary school.

By the middle of the century, deforestation in the Amazon could reduce rainfall by up to 20%, even in areas far from those that have lost trees.

Tropical forests release huge volumes of water to the atmosphere, where it moves around and is recycled as rainfall — but pasture and farmland do not. Delphine Zemp at Humboldt University in Berlin and her colleagues modelled how the loss of forests could affect rainfall across South America. They calculate that if deforestation continues at roughly its current rate, dry-season rainfall will decrease by 8% across the Amazon basin by 2050, with localized hotspots losing up to 20% of their rain.

The greatest reductions in rainfall were seen in the southwestern part of the Amazon, and could make the region more vulnerable to disturbances such as extreme drought and fire. Rainfall loss from deforestation could therefore lead to further environmental degradation.

The ancient inhabitants of Rapa Nui — also called Easter Island — seem to have improved their nutrient-poor land with careful stewardship.

Recent archaeological evidence has challenged the idea that the prehistoric Rapa Nui population caused its own decline by over-exploiting its environment, but how this population used the scarce resources available is still unclear. Catrine Jarman at the University of Bristol, UK, and her colleagues analysed human and animal bones, plant remains and soil from around AD 1400, as well as more modern samples from the island.

The chemical make-up of the human remains shows that around half of the ancient population’s diet came from the sea. Furthermore, the isotopic composition of the agricultural soil suggests that the islanders, famed for their rock carvings, manipulated their gardens to improve crops — probably by using fertilizers.

Astronomers have discovered a puzzling star system in which two bodies orbit each other extremely tightly, without one feeding off the other.

Saul Rappaport at the Massachusetts Institute of Technology in Cambridge and his colleagues, and a separate team led by Steven Parsons at the University of Sheffield, UK, independently discovered the binary system, called WD1202-024, in data from NASA’s Kepler telescope. The researchers noticed that a white dwarf, the remains of a once Sun-like star, was being totally eclipsed every 71.2 minutes. This suggests it is in orbit with a brown dwarf, an object too light to form a normal star.

Rappaport’s team investigated how these bodies could come to orbit each other at less than the distance between Earth and the Moon without the more massive star draining matter from its companion. Their models suggest that the white dwarf’s predecessor probably expanded into a red giant, engulfing the brown dwarf. This caused the less-massive body to spiral inwards, throwing out most of the matter from the giant and leaving it as a white dwarf.

The authors predict that the white dwarf will creep close enough to start feeding off its companion in less than 300 million years.

Aggressive mating practices, previously seen only in humans and chimps, may be more widespread.

Male use of aggression to coerce females into sex may be more widespread than previously thought.

Sexual intimidation, whereby male aggression improves mating success days or weeks later, has until now been documented only in humans and chimpanzees. Alice Baniel at the Institute for Advanced Study in Toulouse, France, and her colleagues found that wild male chacma baboons (Papio ursinus) in Tsaobis Nature Park in Namibia were more aggressive towards fertile females than they were towards females that were pregnant or nursing offspring. Males were responsible for 78% of injuries to female baboons. The more aggression a female received from a given male during her receptive period, the more likely the pair were to mate during her next ovulation. But there was no link between overall male violence and mating.

The authors suggest that sexual intimidation may have been overlooked in primates because of the delay between the act of aggression and its benefit to the male.

In the creation of protected areas, minimizing conflict with agriculture seems to be prioritized over ensuring the survival of animal species.

Oscar Venter at the University of Northern British Columbia in Prince George, Canada, and his colleagues analysed protected areas around the world to show that these areas seem to be created on land that is less valuable than the global average.

Since 2004, more than 40,000 protected areas have been created, totalling more than 3 million square kilometres of land. But these new protected areas are not located in places with high concentrations of species; instead, they are sited on land of low agricultural value.

Reserves created since 2004 have provided protection for 84 threatened vertebrate species, the authors calculate, instead of the more than 3,500 such species that could have been protected if the same area of land had been assigned more strategically.